Substrate carrying device, substrate carrying method and computer-readable storage medium

ABSTRACT

The substrate carrying device includes a carrying passage forming member forming a carrying passage along which a substrate is carried, exhaust grooves extending parallel to the carrying passage in the upper surface of the carrying passage forming member, a plurality of pairs each of right and left carrying gas flow grooves formed in the upper surface of the carrying passage forming member, inclined to a substrate carrying direction so as to approach the exhaust grooves from the right-hand side and the left-hand side of the exhaust grooves, respectively, and having inner ends joined to the exhaust grooves, respectively, and gas spouting pores formed near outer ends of the carrying gas flow grooves to spout a gas for causing the substrate to float and for creating substrate carrying gas flows flowing from the outer ends of the carrying gas flow grooves toward the inner ends of the carrying gas flow grooves.

CROSS REFERENCE

This application is a division of and is based upon and claims thebenefit of priority under 35 U.S.C. §120 for U.S. Ser. No. 11/616,484,filed Dec. 27, 2006, and claims the benefit of priority under 35 U.S.C.§119 from Japanese Patent Application No. 2006-001865, filed Jan. 6,2006. The entire contents of U.S. application Ser. No. 11/616,484 areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate carrying device that floatsa substrate by the agency of a gas, such as air, and carries thefloating substrate, a substrate carrying method, and a computer-readablestorage medium storing programs for accomplishing the substrate carryingmethod.

2. Description of the Related Art

A carrying arm is most prevalently used as a substrate carryingmechanism in a semiconductor device fabricating process. The carryingarm needs a mechanism for advancing and retracting the carrying arm anda mechanism for moving the carrying arm along a carrying passage. Thosemechanisms for a carrying arm for carrying a large substrate areinevitably large. Driving units for driving those mechanisms areconsiderably large when the carrying arm carries, for example, a 12 in.diameter or 16 in. diameter wafer. When such large driving units areused, a dust removing measure, such as creation of special exhaust flow,needs to be taken to suppress the adhesion of particles produced by theabrasion of the driving units to the substrate. A large semiconductordevice fabricating system is needed to process a large substrate.Therefore, the semiconductor device fabricating system needs to be builtin the simplest possible construction.

In view of those necessary conditions, a substrate carrying mechanismthat carries a substrate by a carrying method that floats a substrate bythe agency of a gas and carries the floating substrate is advantageousbecause a carrying device provided with such a substrate carryingmechanism can be built in a thin structure. A known substrate carryingmechanism mentioned in, for example, Patent document 1 carries asubstrate by such a carrying method. This known substrate carryingmechanism will be briefly described with reference to FIGS. 19( a) and19(b) respectively showing this known substrate carrying mechanism in atop view and a longitudinal sectional view. Shown in FIGS. 19( a) and19(b) are a flat structure 11 forming a carrying passage, and a topplate 12 included in the flat structure 11. Many gas spouting pores 13are arranged at intervals all over the top plate 12. The gas spoutingpores 13 extend obliquely through the top plate 12. As shown in FIG. 19(c), the gas spouting pores 13 are formed such that the gas is spoutedobliquely upward in a direction from one end, namely, a first end on theleft-hand side in FIG. 19( c), toward the other end, namely, a secondend on the right-hand side in FIG. 19( c), of the carrying passagethrough the gas spouting pores 13. A bottom member is attached to thetop plate 12 to define a closed space 15. A gas supply pipe 16 has oneend connected to the flat structure 11 and the other end connected to agas source to supply, a compressed gas, such as compressed air, into theclosed space 15.

Compressed air is supplied through the gas supply pipe 16 into theclosed space 15 after the wafer W, namely, a substrate, has been placedon a part of the carrying passage on the side of the first end in thissubstrate carrying mechanism. The air is spouted through the gasspouting pores 13 obliquely upward as shown in FIG. 19( c). The airpushes up the wafer W from the top plate 12 to float the wafer W. Theair flows along the lower surface of the wafer W toward the second endof the carrying passage to propel the floating wafer W toward the secondend of the carrying passage. Thus the wafer W is carried from the firstend to the second end of the carrying passage.

Since any frictional force acts on the floating wafer W, the wafer W isunstable and is moved by a slight force. Thus the substrate is liable tobe caused to drift longitudinally or transversely by a slight force.Therefore, the gas spouting pores 13 need to be precisely formed toprevent the wafer W from drifting away from a correct position. However,it is difficult, in general, to form many pores obliquely to thethickness of such a plate and hence it is possible that the air flow forcarrying the wafer W is disturbed to cause troubles in carrying thewafer W and the substrate carrying mechanism needs a high manufacturingcost.

Air of a high cleanliness must be used for carrying the wafer W so thatthe air may not affect a process for processing the carried wafer Wadversely. Air consumption rate increases with the length of thecarrying passage and hence the running cost of the substrate carryingmechanism is high when the carrying passage is long.

Although methods that use air for carrying a substrate are widely known,practical application of those methods is difficult because of thoseforegoing problems.

For example, a coating and developing system for coating a substratewith a resist film and processing the substrate by a developing processhas many processing units. Those processing units are stacked in layersin processing blocks. Efforts are made to carry a substrate directlyfrom one to the other of the processing unit of the block. Although aflotation carrying mechanism is thin and is advantageous in carrying asubstrate for a long distance. The foregoing problems hinder thepractical application of the flotation carrying mechanism.

Patent document 1: JP-A 57-128940, p. 2, 11. 12 to 17, lower left-handcol.

SUMMARY OF THE INVENTION

The present invention has been made under such circumstances and it istherefore an object of the present invention to provide a flotationsubstrate carrying device capable of being manufactured at a lowmanufacturing cost and of carrying a substrate at a low gas consumptionrate, a substrate carrying method and a storage medium storingcomputer-readable programs for accomplishing the substrate carryingmethod.

A substrate carrying device in a first aspect of the present inventionincludes: a carrying passage forming member forming a carrying passagealong which a substrate is carried; exhaust grooves extending parallelto the carrying passage in the upper surface of the carrying passageforming member; a plurality of pairs each of right and left carrying gasflow grooves formed in the upper surface of the carrying passage formingmember, inclined to a substrate carrying direction so as to approach theexhaust grooves from the right-hand side and the left-hand side of theexhaust grooves, respectively, and having inner ends joined to theexhaust grooves, respectively; and gas spouting pores formed near theouter ends of the carrying gas flow grooves to spout a gas for floatinga substrate and for creating substrate carrying air flows flowing fromouter ends of the carrying gas flow grooves toward inner ends of thecarrying gas flow grooves.

A substrate carrying device in a second aspect of the present inventionincludes: a carrying passage forming member forming a carrying passage;gas spouting pores formed in the carrying passage forming member andarranged along the carrying passage to spout a gas for causing asubstrate to float; and a gas spouting unit disposed above the carryingpassage, provided with gas spouting pores for spouting a carrying gasobliquely downward toward the substrate to produce gas flows flowing ina substrate carrying direction on the carrying passage to carry thesubstrate. Each of those substrate carrying devices may include, forexample, gas supply control means for controlling starting and stoppingsupplying the gas to groups of the gas spouting pores assigned topassage sections defined by longitudinally dividing the carrying passagesuch that the groups of the gas spouting pores start spouting the gasand stop spouting the gas independently, position measuring means formeasuring the position of the substrate on the carrying passage, and acontrol unit for controlling opening and closing operations of the gassupply control means for controlling starting and stopping supplying thegas to the groups of the spouting pores on the basis of measured dataprovided by the position measuring means.

A substrate carrying device in a third aspect of the present inventionincludes: a carrying passage forming member forming a carrying passageextending in a substrate carrying direction; flotation gas spoutingpores formed in the carrying passage forming member and arranged alongthe carrying passage to spout a flotation gas for causing a substrate tofloat; carrying gas spouting pores formed in the carrying passageforming member to create gas flows for carrying the floating substratealong the carrying passage; gas supply control means for controllingstarting and stopping supplying the gas to groups of the gas spoutingpores assigned to passage sections defined by longitudinally dividingthe carrying passage such that the groups of the gas spouting poresstart spouting the gas and stop spouting the gas independently; positionmeasuring means for measuring the position of the substrate on thecarrying passage; and a control unit for controlling opening and closingoperations of the gas supply control means for controlling starting andstopping supplying the gas to the groups of the spouting pores on thebasis of measured data provided by the position measuring means.

The position sensing means are, for example, substrate detectorsdisposed in the passage sections, respectively, to detect the substrate.The substrate carrying device may be provided with floating heightmeasuring means for measuring the floating height of the substrate fromthe carrying passage, and a decision means for deciding whether or notthe substrate is at a predetermined floating height on the basis of thefloating height measured by the floating height measuring means.

A substrate carrying method in a fourth aspect of the present inventionincludes the steps of: placing a substrate on a carrying passage formingmember forming a carrying passage; causing the substrate to float byspouting a gas through gas spouting pores formed in the upper surface ofthe carrying passage forming member, near the outer ends of carrying gasflow grooves inclined to a substrate carrying direction so as toapproach exhaust grooves from the right-hand side and the left-hand sideof the exhaust grooves extending parallel to the carrying passage in theupper surface of the carrying passage forming member, respectively, andhaving inner ends joined to the exhaust grooves; and creating gas flowsflowing from outer ends toward the inner ends of the carrying gas flowgrooves to carry the substrate.

A substrate carrying method in a fifth aspect of the present inventionincludes the steps of: spouting a flotation gas for causing a substrateto float through gas spouting pores formed in a carrying passage formingmember extending in a substrate carrying direction, and arranged along acarrying passage; and creating gas flows flowing in the substratecarrying direction and capable of moving the substrate in the substratecarrying direction by spouting a carrying gas obliquely downward by agas spouting unit disposed above the carrying passage.

A substrate carrying method in a sixth aspect of the present inventionincludes the steps of: spouting a flotation gas through flotation gasspouting pores formed in a carrying passage forming member extending ina substrate carrying direction and arranged along a carrying passage tocause a substrate to float; spouting a carrying gas through carrying gasspouting pores to create gas flows for carrying the substrate along thecarrying passage; making groups of the gas spouting pores assigned topassage sections defined by longitudinally dividing the carrying passagestart and stop supplying the gas independently by gas supply controlmeans; measuring the position of the substrate on the carrying passageby position sensing means; and controlling opening and closingoperations of the gas supply control means for controlling starting andstopping supplying the gas to the groups of the spouting pores on thebasis of measured data provided by the position sensing means.

The substrate carrying method includes, for example, the steps ofmeasuring the position of the substrate on the carrying passage in thecarrying direction; and controlling opening and closing operations ofthe gas supply control means for controlling starting and stoppingsupplying the gas to the groups of the spouting pores assigned to thepassage sections on the basis of measured data obtained in the step ofmeasuring the position of the substrate. The substrate carrying methodincludes, for example, the steps of: measuring the floating height ofthe substrate from the carrying passage; and deciding whether or not thesubstrate is at a predetermined floating height on the basis of measuredfloating height of the substrate. Those steps of the substrate carryingmethod are executed by, for example, a substrate carrying deviceprovided with a computer-readable storage medium storing a programs foraccomplishing the steps of the substrate carrying method, and capable ofcarrying the substrate floating above the carrying passage along thecarrying passage.

In the substrate carrying device of the present invention, thelongitudinal exhaust grooves are formed parallel to the carrying passagein the upper surface of the carrying passage forming member; theplurality of pairs each of right and left carrying gas flow groovesformed in the upper surface of the carrying passage forming member,extending obliquely to a substrate carrying direction so as to approachthe exhaust grooves from the right side and the left side of the exhaustgrooves, respectively, and having inner ends joined to the exhaustgrooves, and the gas spouting pores are formed near the outer ends ofthe carrying gas flow grooves. The gas spouted through the gas spoutingpores floats the substrate and flows through the carrying gas flowgrooves into the exhaust grooves, and gas flows flowing through thecarrying gas flow grooves into the exhaust grooves propel the substrateso as to move along the carrying passage. The carrying passage formingmember can be made by easy machining work because the gas spouting poresneed to be formed to spout the gas merely vertically upward.

The present invention divides the carrying passage longitudinally intothe plurality of passage sections, the position of the substrate on thecarrying passage with respect to the carrying direction, and controlsstarting and stopping supplying the gas to the groups of the gasspouting pores assigned to the passage sections on the basis of themeasured position of the substrate such that the groups of the gasspouting pores start spouting the gas and stop spouting the gasindependently. Therefore, the useless consumption of the gas can besuppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a substrate carrying device in a firstembodiment according to the present invention;

FIG. 2 is a top view of the substrate carrying device in the firstembodiment;

FIG. 3 is a cross-sectional view of the substrate carrying device in thefirst embodiment;

FIG. 4 is a longitudinal sectional view of the substrate carrying devicein the first embodiment;

FIG. 5 is a perspective view of a surface of a carrying passage formingmember, provided with a carrying passage, included in the substratecarrying device in the first embodiment;

FIG. 6 is a longitudinal sectional view of the carrying passage formingmember shown in FIG. 5;

FIG. 7 is plan view showing a wafer being carried along the carryingpassage;

FIG. 8 is a plan view of a carrying gas flow groove and an exhaustgroove formed in the carrying passage forming member;

FIG. 9 is a perspective view of an end part of the carrying passage;

FIG. 10 is a longitudinal sectional view of opposite end parts of thecarrying passage;

FIG. 11 is a schematic side elevation of assistance in explaining amethod of measuring the floating height of a substrate;

FIG. 12 is a diagrammatic view of assistance in explaining thesuccessive starting and stopping of spouting the gas through the groupsof gas spouting pores;

FIG. 13 is a longitudinal sectional view of a substrate carrying devicein a second embodiment according to the present invention in a substratecarrying operation;

FIG. 14 is a plan view of nozzles included in the substrate carryingdevice in the second embodiment;

FIG. 15 is a plan view of a coating and developing system including asubstrate carrying device according to the present invention;

FIG. 16 is a perspective view of the coating and developing system shownin FIG. 15;

FIG. 17 is longitudinal sectional view of the coating and developingsystem shown in FIG. 15;

FIG. 18 is a perspective view of a coating unit, a shelf unit, a mainarm and an exhaust unit include in a DEV layer in the coating anddeveloping system shown in FIG. 15; and

FIG. 19 is a view showing a known substrate carrying device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 4 show a substrate carrying device in a first embodimentaccording to the present invention, in which indicated at 2 is anelongate carrying passage forming plate, namely, carrying passageforming member, forming a carrying passage. The carrying passage formingplate 2 is extended horizontally. An entrance table 3 and an exit table4 are formed at a first end, i.e., a left-hand end as viewed in FIG. 1,and at a second end, i.e., a right-hand end as viewed in FIG. 1,respectively. A U-shaped carrying arm 20 of an external carryingmechanism delivers a semiconductor wafer W (hereinafter, referred tosimply as “wafer”), namely, a substrate, on the entrance table 3. Threelifting pins 41 capable of being vertically moved are arranged on theentrance plate 3. The lifting pins 41 are moved vertically to transferthe wafer W between the carrying arm 20 and the entrance table 3.Similarly, three lifting pins 41 capable of being vertically moved arearranged on the exit plate 3. The lifting pins 41 are moved verticallyto transfer the wafer W between the exit table 4 and a carrying arm, notshown.

The carrying passage forming plate 2 is divided into a plurality ofpassage sections successively arranged in a carrying direction. In FIG.1, the carrying passage forming plate 2 is divided into eight passagesections S1 to S8. The entrance table 3 is the first passage section S1and the exit table 4 is the eighth passage section S8.

For example, pairs of flotation gas spouting pores 22 penetrate thepassage sections S1 to S7 vertically. The pairs of flotation gasspouting pores 22 are arranged in two transversely spaced longitudinalrows, respectively. The pairs of flotation gas spouting pores 22 arearranged at intervals in the carrying direction. The gas is spoutedvertically upward through the flotation gas spouting pores 22 and gasspouting pores 53 to cause the wafer W to float above the carryingpassage forming plate 2.

Two parallel exhaust grooves 51 are formed in the upper surface of thecarrying passage forming plate 2 through the passage sections S1 to S7so as to extend in the carrying direction on the outer side of the tworows of the flotation gas spouting pores 22, respectively. Carrying gasflow grooves 52 are formed in the upper surface of the carrying passageforming plate 2 on the outer side of the exhaust grooves 51,respectively. The carrying gas flow grooves 52 are formed so as toapproach the exhaust grooves 51 in the carrying direction. Inner ends ofthe carrying gas flow grooves 52 are joined to the exhaust grooves 51,respectively. The carrying gas flow grooves 52 are formed in pairsarranged along the carrying passage at intervals. The pairs of carryinggas flow grooves 52 are symmetrical with respect to the center line ofthe carrying passage forming plate 2. Thus the carrying gas flow grooves52 extend obliquely to the exhaust grooves and the inner ends thereofare joined to the exhaust grooves 51, respectively.

The carrying gas flow grooves 52 and parts around the flow grooves 52will be described with reference to FIGS. 5 and 6. FIG. 5 is an enlargedperspective view of the flow grooves 52 and parts around the flowgrooves 52. FIG. 6 is a sectional view taken on the line I-I in FIG. 5.Referring to FIG. 6( a), the carrying gas flow groove 52 has a depth h1between 0.5 and 1.0 mm. The gas spouting pore 53 extends verticallythrough a part of the carrying passage forming plate 2 corresponding toan outer end of the carrying gas flow groove 52. The exhaust groove 51is formed in a depth greater than that of the carrying gas flow groove52 to discharge efficiently air spouted through the gas spouting pore 53through the exhaust groove 51. For example, the exhaust groove 51 has adepth h2 between 1.0 and 2.0 mm.

As shown in FIG. 6( a), the gas spouting pore 53 opening into thecarrying gas flow groove 52 is formed so as to spout air verticallyupward. When the wafer W is above the gas spouting pores 53, air spoutedthrough the gas spouting pores 53 and the flotation gas spouting pores22 pushes up the wafer W to float the wafer W above the carrying passageforming plate 2 and flows into the exhaust grooves 51 as indicated bythe arrows. The air spouted through the gas spouting pores 53 againstthe wafer W is caused to flow into the exhaust grooves 51 by pressuregradient in the vicinity of the gas spouting pores 53. Air flowingthrough the carrying gas flow grooves 52 exerts a longitudinal force ina direction from the entrance table 3 toward the exit table 4 andtransverse forces in directions toward the center line of the carryingpassage on the wafer W. Consequently, the wafer W is moved toward theexit table 4 with its center held on the center line of the carryingpassage. As shown in FIG. 8, the angle θ1 between the respective centeraxis of the carrying gas flow groove 52 and the exhaust groove 51 in ahorizontal plane is, for example, between 30° and 60°. For example, thecarrying gas flow groove 52 has a width 11 between 3 and 10 mm and theexhaust groove 51 has a width 12 between 7 and 20 mm.

The wafer W is carried from the entrance table 3 toward the exit table4. Therefore, air flows through the carrying gas flow grooves 52 intothe exhaust grooves 51 and flows downstream through the exhaust grooves51. Air starts flowing through the upstream carrying gas flow grooves 52on the side of the entrance table 3 and flows successively through thedownstream carrying gas flow grooves 52.

The exit table 4 at the second end of the carrying passage will bedescribed with reference to FIG. 9( a) showing a central part of theexit table 4 in a perspective view. A plurality of positioning gasspouting pores 61, i.e., six positioning gas spouting pores 61 in thisembodiment, are formed in the central part on a first circle having adiameter smaller than that of the wafer W and its center at the centerof the central part. An annular groove 62 is formed along a secondcircle concentric with the first circle and having a diameter smallerthan that of the first circle. Radial positioning gas flow grooves 63extend toward the positioning gas spouting pores 61, respectively, fromthe annular groove 62. The positioning gas flow grooves 63 are used forpositioning the wafer W on the exit table 4. Suction pores 64 are formedin the bottom of the annular groove 63 respectively on the center linesof the positioning gas flow grooves 63. As shown in FIG. 4, a exhaustpipe 65 extended under the carrying passage forming plate 2 has one endconnected to the suction pores 64 and the other end connected through avalve V9 to a suction device 66, such as a vacuum pump, disposed outsidean air chamber, which will be described later.

When the wafer W carried downstream along the carrying passage istransferred from the seventh passage section S7 to the exit table 4, airis spouted through the gas spouting pores 61. Discharge of air throughthe suction pores 64 is started substantially simultaneously with thestart of spouting air through the gas spouting pores 61. Thus air flowsfrom each gas spouting pore 61 through the radial positioning gas flowgroove 63 toward the suction pore 64 as indicated by the arrows in FIG.9( b). The wafer W delivered to the exit table 4 is floated above theexit table 4, is positioned at a predetermined position and heldstationary by the flow of air.

The positional relation between the suction pores 64 and the gasspouting pores 61 on the exit table may be reversed; that is, thesuction pores 64 may be formed at outer ends of the positioning gas flowgrooves 63, respectively, and the gas spouting pores 61 may be formed inthe annular groove 62. When the air is spouted through the gas spoutingpores 61 and is discharged through the suction pores 64 in this state,air flows from the annular groove 62 toward the outer ends of thepositioning gas flow grooves 63. Thus the wafer W may be positioned onthe exit table 4 by air flows flowing radially outward on the exit table4.

The passage sections S1 to S8 are controlled so as to spout the gasthrough the gas spouting pores 22, 53 and 61 independently. As shown inFIG. 4, air chambers 24 are formed under the passage sections 51 to S8by air chamber forming members 24 a, respectively. The respective inletends of the gas spouting pores 22, 53 and 61 open into the air chambers24. In the passage section S1 (the passage section S8), sleeves 32(sleeves 42) are disposed in the air chamber 24 at positionscorresponding to the lifting pins 31 (the lifting pins 41) as shown inFIG. 10. As shown in FIG. 10, the lifting pins 31 (the lifting pins 41)are extended upward from below the air chamber 24 so as to movevertically through the sleeves 32 (the sleeves 42) and bores formed inthe entrance table 3 (the exit table 4). In FIG. 10, indicated at 33(43) is a lifting mechanism for vertically moving a support member 34(support member 44) supporting the lifting pins 31 (lifting pins 41).The carrying passage forming plate 2 may be a single plate or may be asectional plate formed by connecting plates forming the passage sectionsS1 to S8.

Gas supply pipes 25 respectively provided with valves V1 to V8 areconnected to the air chambers 24, respectively. Filters F for removingparticles are placed in the gas supply pipes, respectively. Upstreamends of the gas supply pipes 25 are connected to a main gas supply pipe26 provided with a mass flow controller MFC, namely, a flow regulator,and a valve 10. The main gas supply pipe 26 is connected to a gas source27.

The passage sections S2 to S8 are provided with safer detectors 71, suchas reflex optical sensors, namely, light sensors, or capacitance typesensors, respectively. In this embodiment, the wafer detectors 71 aredisposed at the upstream ends of the passage sections S2 to S8 on thecenter line of the carrying passage. The wafer detectors 71 areconnected to a controller 100 as shown in FIG. 4. The controller 100determines a measured position of the wafer W on the basis of detectionsignals provided by the wafer detectors 71. The controller 100 isprovided with, for example, a program, namely, software, for controllingthe valves V1 to V9 on the basis of the measured position of the waferW.

The program is designed, for example, to open the valve, among thevalves V2 to V9, corresponding to the passage section in which the waferW is detected by the wafer detector 71 among the passage sections S2 toS7 to spout air, and closes the same valve upon the detection of thewafer W by the wafer detector 71 of the downstream passage sectioncontiguous with the former passage section to stop spouting air in theformer passage section. The program includes directions foraccomplishing steps of the operation of the substrate carrying device.For example, the valve V2 is opened when the wafer sensor 71 disposed atthe entrance of the passage section S2 goes ON, and the valve V2 isclosed when the wafer detector 71 disposed at the entrance of thepassage section S3 goes ON.

The controller 100 has a computer provided with a program storage unitstoring the program. The controller 100 reads the program from theprogram storage unit and executes the steps specified by the program. Astorage medium, such as a hard disk, a compact disk, a magnetoopticaldisk or a memory card, storing the program is held in the programstorage unit.

The valve V1 is opened to spout the gas through the gas spouting pores22 and 53 in the first passage section S1, namely, the entrance table 3,for example, in a state where the lifting pins 31 are at their upperpositions, the wafer W is supported on the lifting pins 31, the liftingpins 41 of the exit table 4 are at their lower position, and any wafer Wis not on the exit table 4. The valve V1 is closed when the waferdetector 71 disposed at the entrance of the second passage section S2goes ON to stop spouting the gas through the gas spouting pores 22 and53 in the first passage section S1. The valves V8 and V9 are opened tospout air through the gas spouting pores 61 and to discharge air throughthe suction pores 64 so that air flows through the positioning gas flowgrooves 64 toward the center of the exit table 4 when the wafer detector71 disposed at the entrance of the eighth passage section S8 goes ON.The valves V8 and V9 are closed when the lifting pins 41 are raised totheir upper positions. The program is designed to execute thoseoperations sequentially.

Guide members 72 are arranged in a row and guide members 73 are arrangedin a row on the opposite side edges, respectively, of the passagesections S2 to S7 of the carrying passage forming plate 2 as shown inFIGS. 1 and 3 to prevent the wafer W deviated from a correct course fromfalling off the carrying passage forming plate 2. In FIG. 1, the guidemembers 73 are omitted. The guide members 72 and 73 respectivelycorresponding, for example, the passage sections S2 to S7 are providedwith floating height measuring device for measuring the floating heightof the wafer W from the upper surface of the carrying passage formingplate 2. In this embodiment, floating height measuring devices 74 and75, such as transmission type optical sensors, are disposed with theiroptical axes extended on a lower height level H1 lower than a normalfloating height of, for example, 1.0 mm of the floating wafer W and onan upper height level H2 higher than the normal floating height,respectively, as shown in FIG. 11. The floating height measuring device74 (75) has a light emitter 74 a (75 a) and a light receiver 74 b (75 b)held on the guide members 72 and 73, respectively.

Actually, a plurality of floating height measuring devices like thefloating height measuring device 74 or the floating height measuringdevice 75 are arranged at vertical intervals smaller than the thicknessof the wafer W to detect the wafer in a predetermined floating heightrange.

The controller 100 receives an output signal provided by the lightreceiver 74 b (75 b). The controller 100 provides an alarm signal uponthe reception of an output signal provided by the light receiver 74 b orthe light receiver 75 b. For example, the controller 100 may provide asignal or may display an indication to the effect that the lifting forceacting on the wafer W is excessively low upon the reception of a waferdetection signal from the light receiver 74 b or to the effect that thelifting force acting on the wafer W is excessively high upon thereception of a wafer detection signal from the light receiver 75 b.

The controller 100 is capable of measuring time between the detection ofthe wafer W by the wafer detector 71 of the second passage section S2and detection of the wafer W by the wafer detector 71 of the eighthpassage section S8. The controller 100 is capable of providing an alarmsignal to the effect that the wafer W is stopping in the carryingpassage when the wafer detector 71 of the eighth passage section S8 doesnot detect the wafer W after a predetermined time has elapsed since thedetection of the wafer W by the wafer detector 71 of the second passagesection S2.

The operation of the substrate carrying device in this embodiment willbe described. The wafer W held by the carrying arm 20 is carried to aposition above the entrance table 3 on the first side of the carryingpassage forming plate 2 as shown in FIG. 1. Then, the lifting pins 31are raised to push up the wafer W from the carrying arm 20 and tosupport the wafer W thereon. Subsequently, the carrying arm 20 isretracted, the lifting pins 31 are lowered to place the wafer W on theentrance table 3. Then, the valves V1 and V10 (FIG. 4) are opened tospout air through the flotation gas spouting pores 22 and the gasspouting pores 53 of the entrance table 3, provided that any wafer W isnot placed on the exit table 4 on the second side of the carryingpassage forming plate 2.

The air spouted through the gas spouting pores 22 and 53 causes thewafer W to float above the carrying passage forming plate 2. The airspouted through the gas spouting pores 53 is deflected by the wafer W soas to flow through the carrying gas flow grooves 52 into the exhaustgrooves 51. Since any frictional force is acting on the floating waferW, the wafer W is caused to start moving downstream above the carryingpassage forming plate 2 by the air flowing through the carrying gas flowgrooves 52. The valves V2 to V8 for the passage sections S2 to S8 areclosed while the wafer W is moving above the entrance table 3. The waferdetector 71 of the second passage section S2 detects the wafer W uponthe passage of the wafer past the entrance of the second passage sectionS2. Then, the valve V2 for the second passage section S2 is opened tospout air through the gas spouting pores 22 and 53 of the second passagesection S2.

Thus the wafer W is moved downstream in the second passage section S2.The floating height of the floating wafer W is, for example, 1.0 mm.FIG. 12 shows the relation between the position of the wafer W and anair spouting operation. Suppose that the wafer W is within a rangecorresponding to the third passage section S3. Then, air is spouted onlyin the third passage section S3. The wafer W advances past the boundarybetween the passage sections S3 and S4. Then, the wafer detector 71 ofthe fourth passage section S4 goes ON and the valve V4 is opened tospout air in the fourth passage section S4. Thus the wafer W is causedto float by the air spouted in the passage sections S3 and S4. After thewafer W has advanced past the third passage section S3 and the waferdetector 71 at the entrance of the fourth passage section S4 goes OFF,the valve V3 for the third passage section S3 is closed to stop spoutingair in the third passage section S3.

As the wafer W advances through the passage sections S1 to S8, air isspouted only in the passage sections in which air needs to be spouted.Thus the wafer W is moved downstream by the air flow flowing through thecarrying gas flow grooves 52 to the exit table 4 while the wafer W iscentered on the carrying passage with respect to the center line of thecarrying passage forming plate 2. The wafer detector 71 disposed at theentrance of the exit table 4 goes ON upon the detection of the wafer W.then, the valve V8 is opened to spout air through the gas spouting pores61 and the valve V9 is opened to discharge the air through the suctionpores 64 to create air flows flowing toward the center of the exit table4 in the positioning gas flow grooves 63.

After the wafer W has been centered on the exit table 4, the waferdetector 71 of the exit table 4 goes OFF and the valve V7 is closed tostop spouting air through the gas spouting pores 22 and 53 of theseventh passage section S7. The wafer W tends to move downstream byinertia after the spouting of air through the gas spouting pores 53 ofthe seventh passage section S7. The wafer W is caused to float in astationary state at a predetermined position above the exit table 4 bythe air spouted through the positioning gas spouting pores 63.

Subsequently, the lifting pins 41 is raised to lift up the wafer W andto support the wafer W thereon and the valves V8 and V9 are closed tostop spouting and discharging air. Then, the lifting pins 41 are loweredto place the wafer W on the exit table 4. The wafer W is transferredfrom the exit table 4 to a carrying arm, not shown, by the cooperativeoperations of the lifting pins 41 and the carrying arm and the carryingarm carries the wafer W away from the exit table 4.

If the floating height of the wafer W decreases to the lower heightlevel H1 during the operation for carrying the wafer W due to sometroubles in the gas spouting system, the floating height measuringdevices 74 detects the wafer W and goes ON. Then, the controller 100decides that the lifting force acting on the wafer W is excessively lowand provides an alarm signal. If the lifting force acting on the wafer Wis excessively high and the floating height of the wafer W is increasedto the upper height level H2, the floating height measuring device 75detects the wafer W and goes ON. Then, the controller 100 decides thatthe lifting force acting on the wafer w is excessively high and providesan alarm signal. As mentioned above, a plurality of floating heightmeasuring devices are arranged at vertical intervals not only to detectthe wafer W at floating heights corresponding to the floating heightlevels H1 and H2, but also to detect the wafer W at floating heights ina predetermined floating height range. If the lifting force acting onthe wafer W is lost, the wafer W drops at a position between thefloating height measuring device 74 of the passage section and thefloating height measuring device 74 of the passage section on thedownstream side of the former passage section, and the carryingoperation is stopped, the wafer detector 71 of the eighth passagesection S8 dos not detect the wafer W after the elapse of thepredetermined time since the detection of the wafer W by the waferdetector 71 of the second passage section S2. Then, the controller 100decides that the wafer W is stopped on the carrying passage and providesan alarm signal.

In this embodiment, the two parallel exhaust grooves 51 are formed inthe carrying passage forming plate 2 forming the horizontal carryingpassage along which the wafer W is carried, the carrying gas flowgrooves 52 are formed in pairs arranged along the carrying passage inthe upper surface of the carrying passage forming plate 2 on theright-hand side and the left-hand side of the exhaust grooves 51 so asto approach the exhaust grooves 51 in the carrying direction, the innerends of the carrying gas flow grooves 52 are joined to the exhaustgrooves 51, respectively, and the gas spouting pores 53 are formed inthe outer ends of the carrying gas flow grooves 52, respectively. Airspouted through the gas spouting pores 53 exerts lifting force on thewafer W and is caused to flow into the exhaust grooves 51 by pressuregradient in the vicinity of the gas spouting pores 53. Air flowingthrough the carrying gas flow grooves 52 propels the wafer W to move thewafer W along the carrying passage. Air needs to be spouted verticallyupward through the gas spouting pores 53 and hence the gas spoutingpores 53 are formed vertically in the carrying passage forming plate 2.Therefore, the carrying passage forming plate 2 does not need to beprovided with inclined gas spouting pores through which air is spoutedobliquely upward to cause the wafer W to float and to propel the wafer Win the carrying direction and hence the carrying passage forming plate 2can be made by easy machining work.

The carrying gas flow grooves 52 formed in the right-hand and theleft-hand part of the carrying passage are extended toward the centerline of the carrying passage. Air flowing through the carrying gas flowgrooves 52 exerts force on the wafer W in directions toward the centerline of the carrying passage while the wafer W is being moved in thecarrying direction. Therefore, the wafer W is prevented from driftingtransversely and from deviating from a correct course along the carryingpassage with its center held on the center line of the carrying passage.

The carrying passage forming plate 2 is divided longitudinally into theplurality of passage sections, the position of the wafer W on thecarrying passage with respect to the carrying direction is measured bythe wafer detectors 71, and air is spouted only in the passage sectionscontributing to carrying the wafer W among the passage sections S1 toS8. Thus the passage sections S1 to S8 spout air sequentially as thewafer W is moved successively through the passage sections S1 to S8 andthe passage sections S1 to S8 stop spouting air after the wafer W hasmoved past the passage sections S1 to S8. Thus the substrate carryingdevice can operate at a low air consumption rate.

A substrate carrying device in a second embodiment according to thepresent invention shown in FIG. 13( a) differs from the substratecarrying device in the first embodiment in that the substrate carryingdevice in the second embodiment is not provided with any groovescorresponding to the exhaust grooves 51 and the carrying gas flowgrooves 52 of the first embodiment in its carrying passage, and isprovided with a top plate 81 extended above the carrying passageparallel to the carrying passage, and a plurality of nozzles 82respectively provided with gas spouting pores 83. Air is spouted throughthe gas spouting pores 83 of the nozzles 82 obliquely downward toward asecond end of the carrying passage, i.e., toward an exit table 4.Referring to FIG. 14( a) showing the top plate 81 in a bottom view, thenozzles 82 are arranged in pairs on the top plate 81. The pairs ofnozzles 82 are arranged longitudinally at substantially equal intervals.The axes of the gas spouting pores 83 extend toward the center line ofthe carrying passage.

In the substrate carrying device in the second embodiment shown in FIG.13( a), a wafer W is caused to float above a carrying passage formingplate 2 only by air spouted through flotation gas spouting pores 22, andair is spouted through the nozzle 82 toward the floating wafer W.Consequently, the wafer W is pushed toward the center line of thecarrying passage and is propelled toward the second end of the carryingpassage to move the wafer W along the center line of the carryingpassage. FIG. 13( b) shows the wafer W in a side elevation. as shown inFIG. 13( b), the angle θ2 between a chain line indicating a direction inwhich a gas is spouted through the gas spouting pore 83 and aligned withthe axis of the gas spouting pore 83, and the surface of the wafer W is,for example, between 15° and 45°. FIG. 14( b) shows the wafer W in a topview. As shown in FIG. 14( b), the angle θ3 between the axis of thenozzle 82 and a moving direction in which the wafer W is moved, namely,a direction toward the exit table 4, is, for example, between 120° and180°.

In the substrate carrying device in the second embodiment, air isspouted toward the floating wafer W through the nozzles 82 disposedabove the carrying passage at an angle of depression to the surface ofthe wafer W to propel the wafer W. Since there are only a fewrestrictions on the shape of the nozzles and space for installing thenozzles and hence the substrate carrying device can be easilymanufactured.

In the substrate carrying device shown in FIG. 13( a), the carryingpassage forming plate 2 may be divided into a plurality of passagesections, namely, passage sections S1 to S8, the position of the wafer Won the carrying passage with respect to the carrying direction may bemeasured by wafer detectors 71, operations for spouting air through thenozzles 82 and the flotation gas spouting pores 22 and stopping spoutingair through nozzles 82 and the flotation gas spouting pores 22corresponding to the passage sections S1 to S8 may be controlled on thebasis of the measured position of the wafer W, and an alarm signal maybe provided when a measured floating height of the wafer W is notacceptable.

A semiconductor device fabricating system including the substratecarrying device of the present invention will be described withreference to FIGS. 15 to 18. The semiconductor device fabricating systemis a coating and developing system for coating a wafer W with a resistfilm and developing a latent image formed in the resist film by exposurewith a developer.

FIG. 15 is plan view of the coating and developing system, FIG. 16 is aperspective view of the coating and developing system shown in FIG. 15and FIG. 17 is longitudinal sectional view of the coating and developingsystem shown in FIG. 15. The coating and developing system is installedin a cleanroom filled up with an atmospheric atmosphere. The coating anddeveloping system includes a carrier handling block P1 for receiving andsending out a carrier 120 containing thirteen wafers W, namely,substrates, a processing block P2 including four blocks B1 to B4 and acarrying block M1 stacked up in layers, an interface block P3 and anexposure system P4.

The carrier handling block P1 includes a carrier support table 121capable of supporting a plurality of carriers 120 thereon, a walldisposed behind the carrier support table 121 and provided with closableopenings 122, and a transfer arm C for taking out the wafers W from thecarrier 120 through the closable opening 122. The transfer arm C canmove longitudinally, can move vertically and can turn about a verticalaxis to transfer the wafer W to and to receive the wafer W from each oftransfer stages TRS1 and TRS2 included in the blocks B1 and B2, and canmove along the arrangement of the carriers 120.

The processing block P2 surrounded by a box 124 is disposed behind andjoined to the carrier handling block P1. The processing block P2includes the first block B1 (DEV layer), the carrying block M1, thesecond block B2 (BCT layer) for forming a lower antireflection filmunder a resist film, the third block B3 (COT layer) for carrying out aliquid resist application process, and the fourth block B4 (TCT layer)for forming an upper antireflection film on a resist film stacked up inthat order. The blocks B1 to B4 and the carrying block M1 are extendedbetween the carrier handling block P1 and the interface block P3. TheDEV layer B1 is a developing block, and the BCT layer B2, the COT layerB3 and the TCT layer B4 are coating blocks for forming a film of aresist, namely, a photosensitive material. The adjacent blocks areseparated by partition plates (base members).

The configuration of the first block B1 to the fourth block b4 will bedescribed. In this coating and developing system, the blocks B1 to B4have many common parts and the blocks B1 to B4 are similar in the layoutof component parts. Therefore, the DEV layer B1 will be described by wayof example with reference to FIG. 15. A carrying passage R1 along whicha wafer W is carried is extended longitudinally, i.e., in a directionalong the length of the DEV layer B1 indicated by the arrow Y, in amiddle part of the DEV layer B1 to interconnect the carrier handlingblock P1 and the interface block P3.

A developing unit 300, namely, a wet-processing unit, is extended alongthe carrying passage R1 on the right-hand side, as viewed from thecarrier handling block P1, of the carrying passage R1. The developingunit 300 is provided with a plurality of developing devices for carryingout a developing process using a developer. Four shelf units U1, U2, U3and U4, and an exhaust unit 500 are arranged in that order along thecarrying passage R1 on the left-hand side, as viewed from the side ofthe carrier handling unit P1. Each of the shelf units U1 to U4 hasthermal processing units for heating and cooling stacked in layers. Thedeveloping unit 300, and the shelf units U1 to U4 are disposed on theopposite sides, respectively, of the carrying passage R1. Each of theshelf units U1 to U4 has a thermal processing unit for the pretreatmentof the wafer W before the wafer W is processed by the developing unit300, and a thermal processing unit for the post treatment of the wafer Wafter the wafer W has been processed by the developing unit 300. Thosethermal processing units are stacked in two layers.

The thermal processing units includes heating units for processing thewafer W processed by an exposure process by a heating process, heatingunits for processing the wafer W by a heating process to dry the wafer Wprocessed by a developing process, and cooling units for cooling thewafer W processed by the heating unit to adjust the temperature of thewafer W to a predetermined temperature. In this embodiment, each of theshelf units U1, U2 and U3 has two heating units stacked in two layers,and the shelf unit U4 has two cooling units stacked in two layers.

The carrying block M1 is provided with a substrate carrying device 2Aaccording to the present invention, namely, a direct carrying means forcarrying the wafer W from the carrier handling block P1 directly to theinterface block P3. The substrate carrying device 2A is the foregoingair flotation type substrate carrying device built, for example, inconstruction similar to that shown in FIG. 1. The substrate carryingdevice 2A carries the wafer W from a transfer stage TRS1B correspondingto the entrance table 3 for receiving the wafer W to a transfer stageTRS5B corresponding to the exit table 4 from which the wafer W is sentout.

Areas in the carrying passage R1 and the carrying block M1 contiguouswith the carrier handling block P1 are a first transfer area R2. A shelfunit U5 is installed in the first transfer area R2 as shown in FIGS. 15and 17. The main arm A1, the substrate carrying device 2A and thetransfer arm C can reach the shelf unit U5. A transfer arm D1, namely, avertical carrying means, transfers the wafer W to and receives the waferW from the shelf unit U5.

In the block B1, the transfer stage TRS1B is disposed above the transferstage TRS1. The transfer arms C and D1 can reach the transfer stageTRS1B. The main arm A1, the transfer arm C and the transfer arm D1 canreach the transfer stage TRS1. Each of the transfer stages TRS1 andTRS1B has a rectangular box, a stage provided with a mechanism foradjusting the temperature of the wafer W placed on the stage to apredetermined temperature, and lifting pins capable of being projectedfrom and or being retracted into the stage. Each of the arms advancesinto the box through an opening formed in a wall of the box facing thearms to receive the wafer W lifted up by the lifting pins from thelifting pins or to transfer the wafer W to the lifting pins to place thewafer W on the stage.

As shown in FIG. 17, the blocks B2, B3 and B4 are provided with twotransfer stages TRS2, two transfer stages TRS3 and two transfer stagesTRS4, respectively. All those transfer stages have the forgoingconstruction. The transfer stages TRS2 to TRS4 can transfer the wafer Wto and receive the wafer W from main arms A2, A3 and A4 included in thelayers B2 to B4, respectively, and can transfer the wafer W to andreceive the wafer W from the transfer arm D1. The transfer stages TRS2can also receive the wafer W from and transfer the wafer W to thetransfer arm C. The number of the transfer stages TRS is not limited;each block may be provided with two or more transfer stages.

Areas in the carrying passage R1 and the carrying block M1 of the DEVlayer B1 contiguous with the interface block P3 are a second transferarea R3. A shelf unit U6 is installed in the second transfer area R3 asshown in FIG. 15. The shelf unit U6 is provided with a transfer stageTRS5 and a transfer stage TRS5B disposed above the transfer stage TRS5as shown in FIG. 17. The wafer W can be transferred between the transferstage TRS5B and the interface arm B. The wafer W can be transferredbetween the transfer stage TRS5 and the main arm A1 and between thetransfer arm TRS5 and the interface arm B. The transfer stages TRS5 andTRS5B are the same in construction as the transfer stage TRS1B; thetransfer stages TRS5 and TRS5B have a cooling function to accomplish thetemperature management of the wafer W transferred thereto.

The exposure system P4 is connected to the shelf unit U6 of theprocessing block P2 by the interface block P3. The interface block P3 isprovided with the interface arm B. The interface arm B transfers thewafer W between the shelf unit U6 of the processing block P2 and theexposure system P4. The interface arm B includes, for example, a base,not shown, and an arm, not shown, capable of moving on the base. Acentral part of the wafer W is seated on the arm. The base is supportedon a lifting member by a rotary mechanism so as to be turnable about avertical axis. The base is moved vertically along a vertical rail. Thusthe arm can be advanced and retracted, can be moved vertically and canbe turned about a vertical axis.

The transfer arm D1 is similar in construction to the interface arm B,except that the transfer arm D1 cannot be turned about a vertical axis.

The interface arm B is a wafer carrying means for carrying the wafer Wbetween the processing block P2 and the exposure system P4. In thisembodiment, the interface arm B receives the wafer W from the transferstage TRS5B of the block B1 and carries the same into the exposuresystem P4, and receives the wafer W from the exposure system P4 andtransfers the same to the transfer stage TRS5.

The operation of the coating and developing system will be described interms of the flow of the wafer W during operations for formingantireflection films over and under a resist film, respectively. Acarrier 120 is delivered to the carrier handling block P1. The transferarm C takes out a wafer W from the carrier 120. The wafer W istransferred from the transfer arm C through the transfer stage TRS2 ofthe shelf unit U5 to the main arm A2 of the BCT layer B2. In the BCTlayer B2, the main arm A2 carries the wafer sequentially to the coolingunit, the antireflection film forming unit, not shown and correspondingto the developing unit 300, the heating unit and the transfer stage TRS2of the shelf unit U5 to form a lower antireflection film.

Then, the transfer arm D1 carries the wafer W from the transfer stageTRS2 to the transfer stage TRS3 of the COT layer B3 and transfers thesame to the main arm A3 of the COT layer B3. In the COT layer B3, themain arm A3 carries the wafer W sequentially to the cooling unit and theresist application unit, not shown and corresponding to the developingunit 300, and the heating unit to form a resist film on the lowerantireflection film. Then, the wafer W is carried to an edge exposureunit to process the wafer W by an edge exposure process and the wafer Wis carried to the transfer stage TRS3 of the shelf unit U5.

Subsequently, the transfer arm D1 carries the wafer W from the transferstage TRS3 to the transfer stage TRS4 of the TCT layer B4 and transfersthe same to the main arm A4 of the TCT layer B4. In the TCT layer B4,the main arm A4 carries the wafer W sequentially to the cooling unit,the second antireflection film forming unit, not shown and correspondingto the developing unit 300, and the heating unit to form an upperantireflection film on the resist film. Then, the wafer W is carried tothe transfer stage TRS4 of the shelf unit U5.

Then, the transfer arm D1 carries the wafer W from the transfer stageTRS4 to the transfer stage TRS1B. Then the wafer W is caused to float,is carried to the interface block P3 and is transferred to the transferstage TRS5B by the substrate carrying device of the present invention.The transfer stage TRS5B may be provided with a cooling plate foradjusting the temperature of the wafer W to a temperature suitable forthe exposure process. The interface arm B carries the wafer W from thetransfer stage TRS5B into the exposure system P4. Then, the wafer W issubjected to a predetermined exposure process.

The interface arm B carries the wafer W processed by the exposureprocess to the transfer stage TRS5 of the shelf unit U6. The main arm A1of the DEV layer B1 carries the wafer W from the transfer stage TRS5sequentially to the heating unit, the cooling unit, the developing unit300, the heating unit and the cooling unit of the shelf units U1 to U4to process the wafer W by a predetermined developing process. The waferW processed by the developing process is carried to the transfer stageTRS1 of the shelf unit U5. Then the transfer arm C returns the wafer Winto the carrier 120 held in the carrier handling block P1.

1. A substrate carrying device comprising: a carrying passage formingmember forming a carrying passage along which a substrate is carried;exhaust grooves extending parallel to the carrying passage in the uppersurface of the carrying passage forming member; a plurality of pairseach of right and left carrying gas flow grooves formed in the uppersurface of the carrying passage forming member, angled in a substratecarrying direction so as to approach the exhaust grooves from theright-hand side and the left-hand side of the exhaust grooves,respectively, and having inner ends joined to the exhaust grooves,respectively; and gas spouting pores formed through the carrying passageforming member at a bottom of the carrying gas flow grooves andpositioned near outer ends of the carrying gas flow grooves to spout agas for floating the substrate and for creating substrate carrying airflows flowing from the outer ends of the carrying gas flow groovestoward the inner ends of the carrying gas flow grooves.
 2. The substratecarrying device according to claim 1 further comprising: gas supplycontrol means for controlling starting and stopping supplying the gas togroups of the gas spouting pores assigned to passage sections defined bylongitudinally dividing the carrying passage such that the groups of thegas spouting pores start spouting the gas and stop spouting the gasindependently; position measuring means for measuring a position of thesubstrate on the carrying passage; and a control unit for controllingopening and closing operations of the gas supply control means forcontrolling starting and stopping supplying the gas to the groups of thespouting pores on the basis of measured data provided by the positionsensing means.
 3. The substrate carrying device according to claim 1further comprising: floating height measuring means for measuring afloating height of the substrate from the carrying passage; and adecision means for deciding whether or not the substrate is at apredetermined floating height on the basis of a floating height measuredby the floating height measuring means.
 4. A substrate carrying methodcomprising the steps of: placing a substrate on a carrying passageforming member forming a carrying passage; floating the substrate byspouting a gas through gas spouting pores formed through the carryingpassage forming member at a bottom of the carrying gas flow grooves andpositioned near outer ends of carrying gas flow grooves angled in asubstrate carrying direction so as to approach exhaust grooves from theright-hand side and the left-hand side of the exhaust grooves extendingparallel to the carrying passage in the upper surface of the carryingpassage forming member, respectively, and having inner ends joined tothe exhaust grooves; and creating gas flows flowing from outer endstoward the inner ends of the carrying gas flow grooves to carry thesubstrate.
 5. The substrate carrying method according to claim 4 furthercomprising the steps of: measuring a floating height of the substratefrom the carrying passage; and deciding whether or not the substrate isat a predetermined floating height on the basis of a measured floatingheight.
 6. A non-transitory computer-readable storage medium capable ofbeing read by a computer employed in a substrate carrying device forcausing a substrate to float above a carrying passage forming member andcarrying the floating wafer along a carrying passage, saidcomputer-readable storage medium storing a program for accomplishing thesteps of the substrate carrying method according to claim 4.